1. Field of Invention
This invention relates to a composite material formed by laminating a nonwoven fabric with a low-stress stretchability in one direction and a stretchable layer as an integral. With the lamination of a specific nonwoven fabric with a low-stress stretchability and a stretchable layer as an integral, the composite material advantageously serves as a sheet material that is most useful as a raw material of a sanitary product or the like, such as underwear, dust-proof mask, or dispensable paper diaper etc., is good in processability, stretchability, gas-permeability, softness, and touch, and is difficult to break, i.e., has a high breaking strength.
2. Description of Related Art
Ordinary spunbonded nonwoven fabrics and thermobonded nonwoven fabrics are cheap and widely used as general nonwoven fabrics convenient to use, but almost do not have low-stress stretchability. Though the spunlace nonwoven fabric as a general nonwoven fabric exhibiting low-stress stretchability is now available, its stretchability is not as good as defined in this invention and its cost is relatively high for the characteristic fabricating process. Nonwoven fabrics of low-stress stretchability also include tow-opened nonwoven fabrics with nearly parallel filaments and foam nets obtained by melt extrusion, but they are extremely small in the strength in the cross direction (CD, the width direction in the fabrication of the nonwoven fabric) and cannot meet the requirements of this invention. To solve these problems, some methods have been proposed in the following patent documents.
Patent Document 1 (Japanese Patent Publication no. 1995-54256) describes a laminate of two layers with different shrinkages to form folds on one of the two layers, but the folds are not stretched under a tensile stress.
Patent Document 2 (Japanese Patent Publication no. 2004-521775) describes a neck-stretched nonwoven web, but describes the surface of the nonwoven web to be “flat” and describes formation of folds on the surface of the film laminated with the nonwoven web in accompany with the CD-width reduction of the nonwoven web, which is simply called “width reduction” hereinafter.
Patent Document 3 (Japanese Patent Publication no. 2004-76178) describes using a gear roll to form folds on a nonwoven fabric, but the folds are formed all over the nonwoven fabric with relative large heights and wave lengths that are 2-30 mm and 2-50 mm, respectively.
However, with the above methods, the nonwoven fabric is not soft when being made from multiple layers, or does not have sufficient stretchability; therefore it cannot be the most suitable raw material for a product like underwear or a sanitary product.